. >> reporter: even a strong debate performance by john kerry wasn't enough to defeat george w. bush, but debates matter because it's the first chance to size up the candidates in unscripted moments one-on-one. brian? >> andrea mitchell, who by the way will be our fact checker during our live coverage of the debate wednesday night here on nbc. andrea, thanks. >>> more american deaths today in afghanistan. and the rising death toll numbers will bring more question about the mission in a very unsteady region. tonight we have special coverage of that region, many believe is at the brink, with americans there in harm's way. we have three reports this evening from ann curry, richard engel, and lester holt. we'll begin with lester in kabul in afghanistan. lester, good evening. >> brian, good evening to you. three americans, nearly a dozen others, killed in a suicide bomb attack in the eastern province of khost. for some time now military officials have been saying the taliban have been weakened and are avoiding direct conflict. still they are finding new and effective ways to strike.